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The electrochemical reduction of nitrate to ammonia is of interest as an energy/environmentally friendly source of ammonia for agriculture and energy applications and as a route toward groundwater purification. We report in situ photoemission data, electrochemical results, and density functional theory calculations that demonstrate vanadium oxide—prepared by ambient exposure of V metal, with a distribution of surface V³⁺and V⁴⁺oxidation states—specifically adsorbs and reduces nitrate to ammonia at pH 3.2 at cathodic potentials. Negligible cathodic activity in the absence of NO₃⁻indicates high selectivity with respect to non-nitrate reduction processes. In situ photoemission data indicate that nitrate adsorption and reduction to adsorbed NO₂is a key step in the reduction process. NO₃RR activity is also observed at pH 7, albeit at a much slower rate. The results indicate that intermediate (non-d⁰) oxidation states are important for both molecular nitrogen and nitrate reduction to ammonia.